280
FXUS62 KKEY 080829
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
429 AM EDT Mon Jul 8 2024

...New DISCUSSION, MARINE, AVIATION...

.DISCUSSION...
Issued at 429 AM EDT Mon Jul 8 2024

Warm, humid and dry conditions prevail across the Florida Keys on
this early Monday morning, with one last shower currently dying
out over Florida Bay. Temperatures along the island chain are
hovering in the mid 80s, with dewpoints in the mid to upper 70s,
and winds on land from the southeast to south at 5 to 10 mph.
Surface analysis depicts sprawling high pressure over the Atlantic
and extending westward to the Bahamas, with Hurricane Beryl about
to make landfall along the Texas coast. The Keys lie within
gentle southerly flow between these features. Aloft, a compact
mid/upper level ridge is centered over the Florida peninsula,
between Beryl to the west and a well-defined Tropical Upper
Tropospheric Trough (TUTT) cell spinning well northeast of the
Bahamas. While the 00Z Key West sounding measured PW of 2.04
inches (above the 75th percentile for the date), more recent
MIMIC-TPW and GOES-TPW satellite imagery show a much drier
airmass, with PWs near or below 1.5 inches, advancing NW through
the Old Bahama Channel and eastern Cuba toward our area. This area
of low PWs is associated with a Saharan Air Layer (SAL) moving
through the region.

Slight rain chances will linger across the Keys early this
morning, but the arriving SAL should shut down any convective
activity across the area later this morning. The main weather
concern for today will be the heat, as forecast highs in the lower
90s and dewpoints in the upper 70s push heat indices to 108F or
higher from late morning through the afternoon. Accordingly, a
Heat Advisory has been issued for all of the Keys today.

The SAL will maintain dry weather across the Keys tonight into
Tuesday, but some moisture may begin to return to the eastern
parts of our area by later Tuesday as the weakening TUTT moves
westward into the Florida peninsula. We will probably need a Heat
Advisory for the Keys on Tuesday as high temps should reach the
lower 90s once again with no relief from the high dewpoints.

The latest guidance has continued to keep most of the impact from
the weakening TUTT north of the Keys Tuesday night and Wednesday,
with a ribbon of drier air maintaining itself across our area.
Thus have continued with just slight chance (20 percent) PoPs for
Tuesday night, and low chance (30 percent) PoPs for Wednesday.
These numbers are still above the latest MOS consensus.

Thereafter, we expect a typical midsummer pattern to prevail,
with gentle to moderate easterly flow across the Keys to the
south of the Atlantic ridge. Daily rain chances will be modulated
by subtle changes in moisture, stability and steering flow, along
with any passing weak tropical waves. Have nudged PoPs up to 40
percent for Friday through Saturday, when guidance brings a couple
of such waves through our area. Otherwise, have maintained 30
percent PoPs (slightly above climo) through the rest of the
extended period. Temps will remain near normal, with highs around
90, and lows in the lower to mid 80s outside of any brief
downpours.

&&

.MARINE...
Issued at 429 AM EDT Mon Jul 8 2024

Late night observations show SE to S breezes around 10 knots along
the reef and at Long Key C-MAN. No marine headlines are currently
in effect, and none are expected through the next several days.
From the synopsis, gentle southeast to south breezes will become
east to southeast across the Florida Keys coastal waters today.
High pressure will build westward across the Florida Peninsula and
into the Gulf tonight through the rest of the week, bringing
gentle to occasionally moderate easterly breezes to the Keys
waters for Tuesday through Friday.

&&

.AVIATION...
(06Z TAFS)
Issued at 429 AM EDT Mon Jul 8 2024

VFR conditions will prevail at EYW and MTH today. While an isolated
shower or two cannot be ruled out today, uncertainty in timing and
location as well as below normal chances will leave VCSH out of
either TAF. Near surface winds will be out of the southeast to south
at 6 to 10 knots.

&&

.CLIMATE...
On this day in 1957, the daily record high temperature of 95F was
recorded in Key West. Temperature records for Key West date back
to 1872.

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...Heat Advisory from 11 AM this morning to 6 PM EDT this evening
     for FLZ076>078.

GM...None.
&&

$$

Public/Marine/Fire...Jacobson
Aviation/Nowcasts....JAM

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